1. Field of the Invention
This invention relates to tool holders and in particular to tool holders for holding cutting tools and the like in carrying out machining operations.
2. Description of the Background Art
It is conventional in the machining art to provide tool holders for supporting the tools used in the machining operations on the carrier which may comprise a carriage turret, a tool rest, etc. The tools are supported in the tool holders, or boring bars, and the tools holders or boring bars are, in turn, mounted to the carriers.
A problem arises in the use of such tools in that there is a tendency for the tool to vibrate or chatter during the machining operation. A substantial number of apparatuses and devices have been developed in attempting to solve the problem of such vibration and chattering.
One example of a tool holder having a vibration dampening means is illustrated in U.S. Pat. No. 2,960,189, of John G. Osburn. As shown therein, the tool, comprising a cutter, is operably mounted on an arbor which is secured in a horizontally disposed spindle journaled in a column of the milling machine. In operation, the vibrations of the tool, including the cutter, are transmitted to an overarm, causing it to vibrate transverse to its axis. Friction plates associated therewith move the overarm in the same manner. Masses connected to the overarm tend to remain at rest for a portion of one-quarter of a cycle and then start to move but lag behind the motion of the friction plates by virtue of their inertia so that the masses move in out-of-phase relationship to the friction plates. The resultant relative motion between the plates and masses causes energy of vibration in the overarm to be absorbed and converted into frictional energy which is dissipated as heat.
In Japanese Pat. No. 57-3504, a tool holder is shown to be clamped to a carrier by suitable bolts extending through a pair of pads disposed between the carrier and tool holder. A projection on the tool holder maintains the tool holder spaced from the carrier at opposite sides of the pads.